Method and device for controlling length of yarn of weft knitting machine

ABSTRACT

An object of the invention is to control the yarn length as appropriate in a tubular knitted fabric including a drop loop, regardless of the presence of crossover. For front and back needle beds, ones of those indicated by capitals ABC . . . among odd-numbered or even-numbered ones are allocated to a front portion thereof and the other portions indicated by lower cases abc . . . are allocated to a back portion thereof. At knitting needles ABC . . . which actually form stitch loops perform knitting operation, and knitting needles abc . . . between the knitting needles ABC perform hooking operation. A hung stitch is shook off, and the knitting yarn used for the hanging is absorbed in stitch loops at the knitting needles ABC . . . at both ends as shown in dotted lines. As shown in (b) by solid lines, the loop lengths of back stitches are shortened and the lengths of the knitting yarn at crossing portions are absorbed by the stitch loops of the back stitches. Thus, the drop loops matching the set yarn lengths can be knitted without differentiating the lengths of yarn between the face stitches and back stitches.

TECHNICAL FIELD

The present invention relates to a yarn length control method and devicefor a flat knitting machine for controlling the length of yarn for adrop loop knitted by providing a hung stitch made by hanging yarn over aknitting needle that is not used for producing a knitted fabric, inproducing a tubular knitted article using knitting needles alternatelyin the flat knitting machine provided with the front and the back needlebeds.

BACKGROUND ART

Conventionally, in a flat knitting machine, a knitted fabric is producedin such a manner that a carriage travels back and forth along thelongitudinal direction of the front and the back needle beds opposingeach other at a needle bed gap, knitting needles are moved forward toand backward from the needle bed gap by a knitting lock mounted on thecarriage, and yarn is supplied to the knitting needles from a yarncarrier brought by the carriage. By measuring the length of the yarnabsorbed into the knitted fabric during knitting and by correcting thestitch density positions of stitch cams pulling down the knittingneedles on a knitting lock, it is possible to control the length of theyarn so that the yarn in a knitting stitch loop has a predeterminedlength (refer to Japanese Patent No. 3085638 and Japanese UnexaminedPatent Publication JP-A-8-120548 (1996), for example). Such yarn lengthcontrol can be performed also with a yarn feeding apparatus forsupplying yarn (see JP-A-2002-227064, for example).

Conventionally, the length of a yarn is controlled in different mannersbetween a plain knitted texture knitted using adjacent knitting needlesin the same needle bed and a rib stitch texture knitted using knittingneedles alternately in needle beds opposing each other. This is becausein the case of a rib texture, it is necessary to include yarn crossingthe needle bed gap between the needle beds. Yarn used for knitting isselected among those from a plurality of yarn carriers and supplied. Foreach of the yarn carriers, yarn itself is different, or a route on whichyarn is supplied is different, and thus the length of the yarn iscontrolled based on correction data that is different for each of theyarn carriers. Furthermore, in a carriage, at least with respect to eachof the front and the back needle beds, a stitch cam for performingknitting in a travel to one side in the longitudinal direction and astitch cam for performing knitting in a travel to the other side in thelongitudinal direction are provided. Thus, each of the stitch densitypositions of the four stitch cams in total is corrected and adjusted sothat the constant length of yarn in a knitting stitch loop can beobtained when performing knitting using any stitch cam. In some cases, aplurality of sets of knitting locks are mounted on the carriage so thata plurality of knitting operations can be performed in one travel in thelongitudinal direction of the needle beds. In such cases, the stitchdensity positions of the four stitch cams are corrected for each of thesets of the knitting locks.

Knitted articles that are subjected to be produced in a flat knittingmachine are garments such as sweaters and have a tubular form coveringthe body three-dimensionally. A method has been developed by which in aflat knitting machine provided with the front and the back needle beds,a knitted article that will have a tubular form in the completed stateis produced by knitting main portions of the knitted fabric such as afront body and a back body separately from each other so that theportions have various textures and patterns. However, a final tubularknitted article cannot be obtained unless the partial knitted fabricsknitted separately are joined by sewing. A tubular knitted article canbe produced also in one piece, for example, when while knitting a frontknitted fabric of the tubular knitted article at the front needle bedand a back knitted fabric of the tubular knitted article at the backneedle bed respectively, the knitted fabrics are joined together on bothof the end sides in the knitting width and the knitting yarns are led togo around. In this case, only front stitches are formed on the knittedfabric texture. A knitted fabric texture that is produced using thefront and the back needle beds and that is substantially similar to atexture obtained by producing each of the knitted fabric portionsseparately can be knitted by a method by which a front portion and aback portion of the tubular knitted fabric are allocated to the knittingneedles in each of the needle beds alternately (see JP-B2-3-75656(1991), for example).

FIG. 8 shows an example in which in a flat knitting machine providedwith the front and the back needle beds, knitting needles arealternately allocated to a front portion and a back portion of a tubularknitted fabric. Each of the needle beds is provided with a plurality ofknitting needles arranged with an equal pitch along the longitudinaldirection. The knitting needles are sequentially numbered from one sidein the longitudinal direction and divided into needles with odd numbersand needles with even numbers, and one side shown by capital letters isallocated to knitting of the front portion of the knitted fabric and theother side shown by lower-case letters is allocated to the back portion.With this allocation of the knitting needles, when each of the frontknitted fabric shown by the solid line and the back knitted fabric shownby the broken line is knitted by drawn off stitching, a knitting needleon the back needle bed can be used for knitting the front portion at anyposition such as the position C. Also with respect to the back portion,any knitting needle on the front needle bed can be used in a similarmanner.

In this manner, although the front and the back portions are knitted inone piece in the flat knitting machine provided with the needle beds onwhich the knitting needles are arranged with a pitch of AaBbCc . . . ,each of the portions is equivalent to a portion knitted separately in aflat knitting machine provided with needle beds on which the knittingneedles are arranged in pitches of ABC . . . and abc . . . . In a flatknitting machine, an arrangement pitch of knitting needles is typicallyexpressed in gauge, which is the number of needles in 25.4 mm (1 inch).Thus, in a method such as shown in FIG. 8, using a flat knitting machinewith a gauge of 5, it is possible to knit, in one piece, a tubularknitted fabric that is similar to a fabric obtained when each of theportions is knitted in a flat knitting machine with a gauge of about 2.5to 3.

Referring to FIG. 9, FIG. 9(a) shows yarn pulled down by the knittingneedles in drawn off stitching in which the knitting needles in everysecond line are used, and FIG. 9(b) shows yarn pulled down by theknitting needles with a pitch having the equivalent effect to thatrealized by the drawn off stitching in FIG. 9(a), in whole needleknitting in which all of the knitting needles are used. Morespecifically, in knitting as shown in FIG. 9(a), knitting is performedusing the needle bed as a needle bed with a gauge that is different fromthe gauge expected when whole needle knitting is performed in the needlebed. Herein, in drawn off stitching using every second needles as shownin FIG. 9(a), substantially, knit and miss are performed alternately. Ina knit knitting operation, yarn is pulled down between sinkers shown bythe dashed dotted lines on both sides of each of the knitting needles.The width between the sinkers arranged on both sides of each of theknitting needles in each of the needle beds in FIG. 9(a) is smaller thanthe width between the sinkers arranged on both sides of each of theknitting needles in the needle bed with a different gauge in which thepitch is double, as shown in FIG. 9(b), due to the existence of theadjacent knitting needles. For example, in a case in which knit knittingis performed with the knitting needle B, adjacent knitting needlesthereof are not the knitting needles A and C, but the knitting needles aand b, so that the width between the sinkers is narrow. Thus, when thesame amount of the knitting needles pulled down is set, the length ofthe yarn in knitting stitch loops is short in the case of drawn offstitching. The difference in the lengths of the yarns in the knittingstitch loops results in the difference in the feelings of the knittedarticles. In drawn off stitching, in order to realize the knittingstitch loops that are equivalent to the loops obtained in knitting witha different gauge having the equivalent effect, a method is conceivableby which the amount of the knitting needles pulled down by the stitchcams on the knitting lock is increased, but it is difficult to pull downsufficiently due to restrictions regarding the strength of the knittingyarn and the shape of the cams.

FIG. 10 shows the manner of a drop loop, in drawn off stitching usingevery second needles, which can realize a yarn length that is similar tothe length of a knitting stitch loop obtained by whole needle knittingin a flat knitting machine having a different gauge as shown in FIG.9(b). For example, when knitting stitch loops of a back knitted fabricare held by the knitting needles abc . . . on the front needle bed,first, the knitting stitch loops are transferred to the back needle bedside so as not to be held by the knitting needles abc . . . , a frontknitted fabric is produced by the knitting needles ABC . . . , and theknitting yarn is pulled down by the knitting needles abc . . . on thefront needle bed, as shown in FIG. 10(a). By letting the knittingneedles abc . . . perform a knitting operation again, the knitting yarnpulled down by the knitting needles abc . . . is shook off from theknitting needles abc . . . and absorbed into knitting stitch loopsformed by the adjacent knitting needles ABC . . . , as shown in FIG.10(b). With this drop knitting in which a hung stitch is formed and thenthe stitch is shook off, the length of yarn in a knitting stitch loopcan be made long more easily than repeating knit and miss alternately.

By performing knitting in which a drop loop is used as shown in FIG. 10,in a case in which a tubular knitted fabric is produced by drawn offstitching, the feeling of the produced knitted fabric can be madeequivalent or similar to the feeling of a knitted fabric produced with adifferent gauge. However, by the amount of the knitting yarn absorbedafter shaking of the hung stitch, the formed drop loop has a longerlength than a knitting stitch loop formed by a simple knit knitting, andthus it is impossible to perform knitting so that the length of the yarnis uniform with a sufficient precision in conventional yarn lengthcontrol intended for a stockinette texture and a rib texture.Furthermore, when adjacent knitting needles are separated between thefront and the back needle beds in drawn off stitching, the knitting yarnis necessary for an extra portion crossing the needle bed gap from thehung stitch to a knitting needle in the other needle bed. This extrayarn is absorbed into the drop loop after shaking off the hung stitch,and thus in knitting under the same condition, the length of the yarn inthe drop loop with a crossing portion is longer than that without acrossing portion.

DISCLOSURE OF INVENTION

It is an object of the invention to provide a yarn length control methodand device for a flat knitting machine, capable of controlling the yarnlength as appropriate in a tubular knitted fabric including a drop loop,regardless of the presence of crossover.

The invention is directed to a yarn length control method forcontrolling the length of yarn forming a knitting stitch loop inproducing, in a flat knitting machine provided with a front and a backneedle bed opposing to each other at a needle bed gap, a tubular knittedarticle in which a front knitted fabric and a back knitted fabric arejoined together at both ends thereof in a knitting width direction,while allocating a plurality of knitting needles which are arrangedalong a longitudinal direction of each of the needle beds, alternatelyto the front knitted fabric that is produced basically at the frontneedle bed and to the back knitted fabric that is produced basically atthe back needle bed so that drawn off stitch is performed, and moving acarriage mounted on a knitting lock which lets each of the knittingneedles perform a knitting operation, along the longitudinal direction,wherein when knitting with knitting needles allocated to each of theknitted fabrics, a hung stitch is formed by hanging yarn over knittingneedles that are adjacent to the knitting needles performing theknitting which are on the front needle bed for the front knitted fabricor on the back needle bed for the back knitted fabric which are under acondition of retaining no knitting stitch loop, and the hung stitch isshook off, and a knitting stitch loop formed on the knitting needleswhich have performed knitting is taken as a drop loop, and

wherein a length of yarn used for knitting the drop loop is controlledto be a predetermined constant yarn length in such a manner that thelength of yarn is separated for a front knitted fabric and a backknitted fabric, and further separated based on whether knitting needlesfor knit knitting that are adjacent to each other having a hung stitchtherebetween belong to a same needle bed or belong to the other needlebed.

The invention is further directed to a yarn length control device forcontrolling a length of yarn forming a knitting stitch loop inproducing, in a flat knitting machine provided with a front and a backneedle bed opposing to each other at a needle bed gap, a tubular knittedarticle in which a front knitted fabric and a back knitted fabric arejoined together at both ends thereof in a knitting width direction,while allocating a plurality of knitting needles which are arrangedalong a longitudinal direction of each of the needle beds, alternatelyto the front knitted fabric that is produced basically at the frontneedle bed and to the back knitted fabric that is produced basically atthe back needle bed so that drawn off stitch is performed, and moving acarriage mounted on a knitting lock which lets each of the knittingneedles perform a knitting operation, along the longitudinal direction,the yarn length control device comprising:

yarn length setting means for setting a length of a drop loop, aknitting stitch loop formed on the knitting needles which have performedknitting, in such a manner, being taken as the drop loop, that whenknitting with knitting needles allocated to each of the knitted fabrics,a hung stitch is formed by hanging yarn over knitting needles that areadjacent to the knitting needles performing the knitting which are onthe front needle bed for the front knitted fabric or on the back needlebed for the back knitted fabric which are under a condition of retainingno knitting stitch loop, and the hung stitch is shook off; and

yarn length control means for controlling a length of yarn used forknitting the drop loop to be a predetermined constant yarn length insuch a manner that the length of yarn is separated for a front knittedfabric and a back knitted fabric, and further separated based on whetherknitting needles for knit knitting that are adjacent to each otherhaving a hung stitch therebetween belong to a same needle bed or belongto the other needle bed.

Furthermore, the invention is characterized in that in the yarn lengthcontrol means, a discrimination between the front knitted fabric and theback knitted fabric is performed based on the needle bed on which aknitting operation of forming a hung stitch or of shaking off a hungstitch is performed.

Furthermore, the invention is characterized in that the carriage cansupply yarn to the needle bed gap via a plurality of routes, and

the yarn length control device further comprises yarn length adjustmentmeans for executing a loop length routine in which for each of theroutes, with respect to the front knitted fabric and the back knittedfabric, the length of the knitted fabric used when knitting the droploop is adjusted to be the yarn length set by the yarn length settingmeans.

BRIEF DESCRIPTION OF DRAWINGS

Other and further objects, features, and advantages of the inventionwill be more explicit from the following detailed description taken withreference to the drawings wherein:

FIG. 1 is a view showing a state how knitting needles performing yarnlength control on drop loops are used in an embodiment of the invention;

FIG. 2 is a perspective view showing an appearance configuration of aflat knitting machine 1 performing the yarn length control in FIG. 1;

FIG. 3 is a view showing a simplified arrangement of cams on a knittinglock mounted on a carriage 6 in FIG. 2;

FIG. 4 is a block diagram showing an electrical configuration performingthe yarn length control in FIG. 1;

FIG. 5 is a flowchart showing a schematic procedure of a loop lengthroutine for a drop loop performed in the yarn length control in FIG. 1;

FIG. 6 is a table showing an example of stitch cam correction data 33 inFIG. 4;

FIG. 7 is a table showing an example of the correspondence of stitch camcorrection data used with respect to a knitting texture in the yarnlength control in FIG. 1;

FIG. 8 is a view showing a method for knitting a tubular knitted fabricby conventional drawn off stitching;

FIG. 9 is a view showing cases where drawn off stitching and wholeneedle knitting are performed with an equal pitch, by comparison; and

FIG. 10 is a view showing the procedure of knitting a drop loop.

BEST MODE FOR CARRYING OUT THE INVENTION

Now referring to the drawings, preferred embodiments of the inventionare described below.

FIG. 1 shows the manner of yarn length control, in a flat knittingmachine, which is an embodiment of the invention. FIG. 1(a) shows a casein which the front needle bed is used to knit a front knitted fabric ofa tubular produced article only with front stitches of drop loops, andFIG. 1(b) shows a case in which the back needle bed as well as the frontneedle bed is used to knit a front knitted fabric including frontstitches and back stitches. In a similar manner to that in FIGS. 8 to10, on the front and the back needle beds, one side shown by capitalletters ABC . . . is allocated to the front knitted fabric, and theother side shown by lower-case letters abc . . . is allocated to theback knitted fabric. The knitting needles ABC . . . actually formingknitting stitch loops perform knit knitting, and the knitting needlesabc . . . between the knitting needles ABC . . . perform hook knitting.The knitting needles in both of the needle beds are numbered from oneside in the longitudinal direction of the needle bed gap and dividedinto needles with odd numbers and needles with even numbers, and thenone side is shown by capital letters ABC . . . and the other side isshown by lower-case letters abc . . . .

The knitting needles abc . . . performing hook knitting are allocated tothe back knitted fabric of the tubular knitted article, and there is apossibility that the knitting needles abc . . . on the front needle bedare also used for knitting back stitches of the back knitted fabric.When knitting stitch loops of the back knitted fabric are hooked on theknitting needles abc . . . on the front needle bed, prior to knitting ofthe front knitted fabric, the knitting stitch loops are held by theopposing knitting needles abc . . . on the back needle bed, so that theknitting stitch loops are not hooked on the knitting needles abc . . .on the front needle bed. When these knitting needles abc . . . that donot have knitting stitch loops are led to perform a knitting operationand yarn is supplied, the knitting yarn is pulled down by the knittingneedles abc . . . to form hung stitches as shown by the solid line. Whenthe knitting needles abc . . . that have pulled down the knitting yarnare selected again and an operation of knit knitting is performed, theknitting yarn is released from the knitting needles through knock-over.Since the knitting needles abc . . . do not hold any other knittingstitch loop, the knitting yarn after the knock-over cannot form a newknitting stitch loop, the hung stitches are shook off, and the knittingyarn used for the hung stitches is absorbed into the knitting stitchloops on the knitting needles ABC . . . , which are arranged on bothsides thereof, as shown by the broken line.

In this embodiment, as shown by the solid line in FIG. 1(b), the amountof the knitting yarn pulled down when performing knit knitting on thefront knitted fabric with the knitting needles at the back needle bed iscorrected to be smaller than the amount of the knitting yarn pulled downwhen performing knit knitting at the front needle bed. With thisprocedure, the knitting yarn by the length for the crossing portions isabsorbed into the knitting stitch loops of the back stitches, and thusit is possible to knit drop loops in which the length of the yarn is notdifferent between the front stitches and the back stitches as shown bythe broken line and matches a predetermined yarn length.

The knitting needles abc . . . for forming hung stitches may be selectedin a tuck state as well as a knit state because it is sufficient thatthe needles can pull down the knitting yarn supplied at the needle bedgap. The back knitted fabric of the tubular knitted article can beproduced in a similar manner to that of the front knitted fabric exceptthat hung stitches are formed on the knitting needles ABC . . . on theback needle bed and the knitting needles abc . . . on the front and theback needle beds are used for knit knitting.

FIG. 2 shows an appearance configuration of a flat knitting machine 1used for knitting in this embodiment. The flat knitting machine 1 has afront needle bed 2 and a back needle bed 3. The front needle bed 2 andthe back needle bed 3 are arranged so that their longitudinal directionsare in parallel, on the front side in the flat knitting machine 1.Needle grooves are formed along the longitudinal directions with anequal pitch, and a knitting needle 4 is disposed in each of the needlegrooves in a slidable manner. The front needle bed 2 and the back needlebed 3 are arranged in such a manner that the front and the back needlebeds are opposed to each other at a needle bed gap 5 positionedtherebetween, their heights increase at the needle bed gap 5, the frontneedle bed 2 is lowered on the front side, and the back needle bed 3 islowered on the back side, so that the needle beds are inclined in theform of a mountain when viewed from the side. The knitting needle 4 isled to move the front end thereof forward to and backward from theneedle bed gap 5 and a knitting operation is thus performed. Theknitting operation of the knitting needle 4 is performed in accordancewith travels of a carriage 6 that can travel back and forth in thelongitudinal direction of the front needle bed 2 and the back needle bed3. On the carriage 6, a knitting lock with which the knitting needle 4can be selectively driven and led to perform a knitting operation by theaction of cams is mounted. The carriage 6 lets the knitting needle 4perform a knitting operation and selectively brings a yarn feedingmember called, for example, a yarn carrier along a yarn guide rail 7extended above the needle bed gap 5 so that yarn 10 can be supplied tothe front end of the knitting needle 4.

The knitting yarn 10 is supplied while being wound up as a corn 11. Fromthe corn 11, the yarn is guided to a yarn feeding member at the yarnguide rail 7, while a tensile force is adjusted via an upper springdevice 12 and a side tension device 13 and the length of the yarn ismeasured by a yarn length measuring device 14. The yarn length measuringdevice 14 measures the length of yarn supplied for knitting, forexample, by a rotary encoder. A controller 15 controls the stitch camson a knitting lock mounted on the carriage 6 and the amount of theknitting yarn 10 sent out at a yarn feeding mechanism so that the lengthof the yarn measured by the yarn length measuring device 14 is apredetermined yarn length.

FIG. 3 shows a simplified configuration of a knitting lock 20 that cancontrol the length of yarn. The carriage 6 shown in FIG. 2 is providedwith knitting cams and needle selecting mechanisms that can let theknitting needle 4 perform an knitting operation selectively for eitherthe front needle bed 2 or the back needle bed 3. The amount of yarnpulled down by the knitting needle 4 in knit knitting or tuck knittingis determined by pulling-down cams, correctively called stitch cams 21.On the knitting lock 20, at least four stitch cams 21FR, 21FL, 21BR, and21BL are provided. The stitch cams 21FR and 21FL pull down the knittingneedle 4 on the front needle bed 2 respectively when the carriage 6travels to the right and the left when viewed from the front to performknitting. The stitch cams 21BR and 21BL pull down the knitting needle 4on the back needle bed 3 respectively when the carriage 6 travels to theright and the left when viewed from the front to perform knitting. Insome cases, a plurality sets of such knitting locks 20 are mounted onthe carriage 6. The positions of the stitch cams 21 can be digitallycontrolled with displacement by a mechanism utilizing, for example, astepping motor.

FIG. 4 schematically shows an electrical configuration performing theyarn length control in this embodiment. The controller 15 shown in FIG.2 includes a CPU 25 controlling the entire flat knitting machine 1 basedon a preset program. The CPU 25 is connected to an interactiveinput/output device 27, a knitting data input device 28, a stitch camadjustment motor 29, a storage device 30, and the yarn length measuringdevice 14, via a bus 26. The interactive input/output device 27 includesa key switch and a pointing device with which various instructions forthe flat knitting machine 1 are input by an operator knitting a knittedfabric with the flat knitting machine 1, and a display device fordisplaying various types of information provided by the flat knittingmachine 1. In the knitting data input device 28, data of a knittedfabric to be produced is input in the form stored in a storage mediumsuch as a flexible disk (FD), a compact disk (CD), a magneto-opticaldisk (MO), and a mini disk (MD), or in the form of wired or wirelessinformation communications. The stitch cam adjustment motor 29 drives toadjust each of the positions of the stitch cams 21FR, 21FL, 21BR, and21BL shown in FIG. 3.

The storage device 30 is realized by, for example, a hard disk or anonvolatile semiconductor memory, and stores program codes and dataincluding a loop length routine 31, stitch cam data 32, and stitch camcorrection data 33. The loop length routine 31 is an object program forknitting a knitting stitch loop including a drop loop with yarn of aspecified length. The stitch cam data 32 shows standard positions of thestitch cams corresponding to the loop length that is to be set. Thestitch cam correction data 33 is correction data for correcting, inaccordance with the loop length routine 31 and the actual knittingoperation, an error between a measured value of the yarn length at theyarn length measuring device 14 and a predicted value of the yarn lengthcalculated based on knitting data. The loop length routine 31 isperformed prior to knitting of a knitted article. When knitting iscontinued, the loop length routine 31 can be set to be performed after apredetermined number of knitted articles have been produced. Also, theloop length routine 31 can be manually executed by the operator.

FIG. 5 shows a schematic procedure of the loop length routine for a droploop executed in this embodiment. The procedure starts in step s0, andin step s1, the drop loop length is input to set the yarn length. It isalso possible that a default value is determined based on, for example,gauge, and the length is set to the default value when there is noinput. In step s2, the positions of the stitch cams corresponding to theinput drop loop length are set based on the stitch cam data 32, toexecute the loop length routine for knitting a drop loop without acrossing portion as shown in FIG. 1(a). In the drop length routine, ameasured value and a theoretical value of the knitting yarn used forknitting are compared in every travel of the carriage 6, to calculatethe stitch cam correction data 33 in which the measured value matchesthe theoretical value or is within a predetermined range. In step s3,the stitch cam correction data 33 calculated for the front needle bed 2is set as data F, and the stitch cam correction data 33 calculated forthe back needle bed 3 is set as data B, in the storage device 30. Instep s4, the loop length routine for a drop loop with a crossing portionis executed. In step s5, the stitch cam correction data 33 obtained byknitting a hung stitch at the front needle bed 2 and a back stitch atthe back needle bed 3 is stored as data B′, and the stitch camcorrection data 33 obtained by knitting a back stitch at the frontneedle bed 2 and a hung stitch at the back needle bed 3 is stored asdata F′, in the storage device 30, respectively. In the step s6, theloop length routine for a drop loop ends.

In conventional yarn length control for producing knitted fabricssolely, the loop length routine is executed with respect to astockinette texture and a rib texture, so that corresponding stitch camcorrection data is obtained. Also in a case in which a tubular knittedfabric is produced using the front needle bed 2 and the back needle bed3, it is preferable that the loop length routine and the stitch camcorrection data, with respect to drawn off stitching, for thestockinette texture and the rib texture are prepared. The stockinettetexture in needle miss routine includes knit and miss alternately asdescribed above. Furthermore, the rib texture in needle miss routine, itis necessary to adjust the length of the knitting yarn for a portioncrossing the needle bed gap.

FIG. 6 shows an example of the stitch cam correction data 33 for a droploop shown in FIG. 4. As the stitch cam correction data 33, stitch camcorrection tables for F and B without a crossing portion shown in FIG.6(a) with respect to a front stitch and stitch cam correction tables forF′ and B′ with a crossing portion shown in FIG. 6(b) with respect to abackstitch are managed separately. Each of the data sets are dividedbetween a case L in which the carriage 6 travels to the left when viewedfrom the front and a case R where the carriage 6 travels to the right.For each of the cases L and R, data based on a result obtained byexecuting the loop length routine for each yarn carrier is stored. Whenthe number of systems of the knitting lock 20 as shown in FIG. 3 isplural, for example, four, data is managed separately from S1 to S4. Thenumbers 1, 2, 3, 4, . . . lined from top to bottom in the left columnshow the yarn carrier numbers. The stitch cam correction data 33 is setfor each of the yarn carrier numbers, and the signs of plus and minusrespectively correspond to an increase and a decrease of the amount ofyarn pulled down. The stitch cam correction tables for F′ and B′ for abackstitch have a correction value such as from −15 to −25, which issmaller than that of the stitch cam correction tables for F and B for afront stitch. More specifically, the length of yarn in knitting stitchloops in knit knitting is made shorter.

The stitch cam correction tables are updated by executing the looplength routine as described above, but also during knitting, it ispossible to update the stitch cam correction tables for each course bycomparing a measured value and a theoretical value of the yarn length,for example, in each course. FIG. 7 shows the correspondence of stitchcam correction data used with respect to a knitting texture in thisembodiment. First, it is checked whether or not there is a drop knittinginstruction, and in a case where there is a drop knitting instruction,it is determined that drop knitting is performed. Next, it is determinedwhich needle bed between the front needle bed 2 and the back needle bed3 forms front stitches or back stitches and the stitch cam correctiontables are selected. More specifically, it is possible to automaticallydetermine that a front knitted fabric is being formed when hung stitchesare provided at the front needle bed 2 and that a back knitted fabric isbeing formed when hung stitches are provided at the back needle bed 3.Furthermore, it is also possible to manually set control data so as todetermine which needle bed between the front needle bed 2 and the backneedle bed 3 forms front stitches or back stitches. In “stockinettetubular stitch” in which tubular plain stitch is performed by knitting afront knitted fabric and a back knitted fabric as a stockinette textureonly with front stitches at the front needle bed 2 and the back needlebed 3, knit and hung stitch are alternately performed at the frontneedle bed 2 and the back needle bed 3 to use the stitch cam correctiontables for F and B respectively. In various types of wide rib knitting,for example, the stitch cam correction tables for F and B are used forfront stitches and the stitch cam correction tables for B′ and F′ areused for back stitches. By using the stitch cam correction tables in asappropriate as described above, it is possible to knit knitting stitchesof drop loops with the constant yarn length.

In this embodiment as described above, the yarn length of one drop loopis defined based on Equation (1) below.one drop loop length=one knit loop length+one hung stitchlength  Equation (1)

Based on this equation, one drop loop length>one knit loop length can beobtained. In order to make the drop loop length equal to the knit looplength at a different gauge realizing an effect obtained in whole needleknitting that is equivalent to drawn off stitching, a necessary hungstitch length in Equation (1) is approximately from 60 to 30% of oneknit length. One tuck length is approximately 90 to 80% of one knitlength, and one miss length is approximately 10% of one knit length, sothat Equation (2) below is obtained.one knit length>one tuck length>one hung stitch length>one misslength  Equation (2)

Thus, at least one of the hung stitch length and the drop loop lengthcannot be substituted by the knit length, the tuck length, or the misslength as a basic knitting stitch loop, and thus independent setting isrequired.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and the rangeof equivalency of the claims are therefore intended to be embracedtherein.

INDUSTRIAL APPLICABILITY

As described above, according to the invention, when performing needlemiss knit knitting with a knitting needle allocated to each of a frontknitted fabric and a back knitted fabric of a tubular knitted fabric, ahung stitch is formed on an adjacent knitting needle, on the frontneedle bed in the case of the front knitted fabric or on the back needlebed in the case of the back knitted fabric, a knitting stitch loopformed by shaking off the hung stitch is taken as a drop loop, and yarnlength control is thus performed. Thus, it is possible to knit aknitting stitch loop with a stable yarn length also for the drop loop.Furthermore, the yarn length is controlled to be a predeterminedconstant yarn length, by determining that the front knitted fabric isbeing formed in the case where a knitting needle on which a hung stitchis formed is the front needle bed and that the back knitted fabric isbeing formed in the case of the back needle bed, and separately based onwhether knitting needles for knit knitting that are adjacent to eachother having a hung stitch therebetween belong to the same needle bed orbelong to different needle beds. Thus, regardless of a crossing portion,it is possible to knit a drop loop with a high precision.

Furthermore, according to the invention, it is possible to knit a droploop by combining knit knitting and a hung stitch, while the yarn lengthis controlled by the yarn length control means so that the yarn lengthof the drop loop set by the yarn length setting means matches the yarnlength of the drop loop that is to be knitted. In the yarn lengthcontrol means, by discriminating between the front knitted fabric andthe back knitted fabric based on whether a needle bed to which aknitting needle forming a hung stitch belongs is the front needle bed orthe back needle bed, and separately based on whether knitting needlesfor knit knitting that are adjacent to each other having a hung stitchtherebetween belong to the same needle bed or belong to different needlebeds, the yarn length is controlled to be the yarn length set by theyarn length setting means. Thus, regardless of a crossing portion, it ispossible to knit a drop loop with a high precision.

Furthermore, according to the invention, it is determined that the frontknitted fabric is being formed in the case where a hung stitch is formedor a hung stitch is shook off on the front needle bed, and it ispossible to easily determine that correction for the case including acrossing portion is necessary to be performed in the case where theneedle bed is the back needle bed.

Furthermore, according to the invention, a drop loop is adjusted by theyarn length adjustment means so as to have the yarn length set by theyarn length setting means, for each route of a plurality of routes onwhich yarn is supplied to the needle bed gap, with consideration tovarious elements. Thus, it is possible to perform knitting so that theyarn length of the drop loop matches a predetermined value.

1. A yarn length control method for controlling the length of yarnforming a knitting stitch loop in producing, in a flat knitting machineprovided with a front and a back needle bed opposing to each other at aneedle bed gap, a tubular knitted article in which a front knittedfabric and a back knitted fabric are joined together at both endsthereof in a knitting width direction, while allocating a plurality ofknitting needles which are arranged along a longitudinal direction ofeach of the needle beds, alternately to the front knitted fabric that isproduced basically at the front needle bed and to the back knittedfabric that is produced basically at the back needle bed so that drawnoff stitch is performed, and moving a carriage mounted on a knittinglock which lets each of the knitting needles perform a knittingoperation, along the longitudinal direction, wherein when knitting withknitting needles allocated to each of the knitted fabrics, a hung stitchis formed by hanging yarn over knitting needles that are adjacent to theknitting needles performing the knitting which are on the front needlebed for the front knitted fabric or on the back needle bed for the backknitted fabric or on the back needle bed for the back knitted fabricwhich are under a condition of retaining no knitting stitch loop, andthe hung stitch is shook off, and a knitting stitch loop formed on theknitting needles which have performed knitting is taken as a drop loop,and wherein a length of yarn used for knitting the drop loop iscontrolled to be a predetermined constant yarn length in such a mannerthat the length of yarn is separated for a front knitted fabric and aback knitted fabric, and further separated based on whether knittingneedles for knit knitting that are adjacent to each other having a hungstitch therebetween belong to the same needle bed or belong to the otherneedle bed.
 2. A yarn length control device for controlling a length ofyarn forming a knitting stitch loop in producing, in a flat knittingmachine provided with a front and a back needle bed opposing to eachother at a needle bed gap, a tubular knitted article in which a frontknitted fabric and a back knitted fabric are joined together at bothends thereof in a knitting width direction, while allocating a pluralityof knitting needles which are arranged along a longitudinal direction ofeach of the needle beds, alternately to the front knitted fabric that isproduced basically at the front needle bed and to the back knittedfabric that is produced basically at the back needle bed so that drawnoff stitch is performed, and moving a carriage mounted on a knittinglock which lets each of the knitting needles perform a knittingoperation, along the longitudinal direction, the yarn length controldevice comprising: yarn length setting means for setting a length of adrop loop, a knitting stitch loop formed on the knitting needles whichhave performed knitting, in such a manner, being taken as the drop loop,that when knitting with knitting needles allocated to each of theknitted fabrics, a hung stitch is formed by hanging yarn over knittingneedles that are adjacent to the knitting needles performing theknitting which are on the front needle bed for the front knitted fabricwhich are under a condition of retaining no knitting stitch loop, andthe hung stitch is shook off; and yarn length control means forcontrolling a length of yarn used for knitting the drop loop to bepredetermined constant yarn length in such a matter that the length ofyarn is separated for a front knitted fabric and a back knitted fabric,and further separated based on whether knitting needles for knitknitting that are adjacent to each other having a hung stitchtherebetween belong to a same needle bed or belong to the other needlebed.
 3. The yarn length control device of claim 2, wherein in the yarnlength control means, a discrimination between the front knitted fabricand the back knitted fabric is performed based on the needle bed onwhich a knitting operation of forming a hung stitch or of shaking off ahung stitch is performed.
 4. The yarn length control device of claim 2or 3, wherein the carriage can supply yarn to the needle bed gap via aplurality of routes, and the yarn length control device furthercomprises yarn length adjustment means for executing a loop lengthroutine in which for each of the routes, with respect to the frontknitted fabric and the back knitted fabric, the length of the knittedfabric used when knitting the drop loop is adjusted to be the yarnlength set by the yarn length setting means.
 5. The yarn length controldevice of claim 3, wherein the carriage can supply yarn to the needlebed gap via a plurality of routes, and the yarn length control devicefurther comprises yarn length adjustment means for executing a looplength routine in which for each of the routes, with respect to thefront knitted fabric and the back knitted fabric, the length of theknitted fabric used when knitting the drop loop is adjusted to be theyarn length set by the yarn length setting means.